Automatic draft regulator



April 24, 1956 R. 1.. HUBBARD 2,743,056

AUTOMATIC DRAFT REGULATOR Filed Sept. 19, 1952 Fig.1. Fig.2 q.

Iii 18,4

INVENTOR.

3L 4 28 RALPH L. HUBBARD United States Patent AUTOMATIC DRAFT "REGULATOR "RalphL. Hubbard, BaileysrHarbor, Wis.

Application September, I952,v Serial No. 310,481

' 2 Claims. (Cl. 236-45) This invention relates to automatic draft regulators and more particularly to a combined check draft and damper assembly adapted to be connected into a conduit such 'as a furnace fluepipe or stack, for maintaining the rate of fluid flow or draft at a predetermined rate through the conduit.

It is-larnong the objects of the invention to .provide an improved .flow regulator which is incorporated in a section of fluid conduit or pipe which can be incorporated into a conduit such as the flue pipe line of a furnace be- .tween the furnace and an associated chimney or flue;

which is responsive to the velocity and pressure of flue gases passing through the pipe section and to the pressure -of the surrounding air to maintain the draft substantially at a predetermined rate; which regulated the rate of fluid flow through the conduit by variably restricting the fluid passage through the conduit section and by the admission of outside air in regulated quantities tothe interior of the conduit; and which is simple and durable in construction, economical .to manufacture, easy to install, and effective and efiicient in operation.

Other objects and advantages will .become apparent from a consideration of the following description and theiappend'ed claims in conjunction with the accompanying, drawing, wherein:

Figure l .is a side elevational view of a draft regulator illustrative of the invention;

Figure 12 is a transverse cross sectional view on the line 2-2 of Figure 1; v

'Figure 3 is a longitudinal cross sectional view on the line 3-3 of Figure 2; and

Figure 4 is a longitudinal cross sectional view on the line 4-4 of Figure 3.

With continued reference to the drawing, the numeral generally indicates a flue pipe'section of cylindrical shape having one end slightly reduced in diameter by corrugations 11 so that this end willflt into the adjacent end ofan associatedpipe section or elbow and having .an opening. 12 of elongated,.rectangular shape therein and extending longitudinally thereof with the ends of the opening spaced substantially equal distances from the respectively opposite ends of the pipe section.

The numeral 14 generally indicates a housing disposed on the pipe section 10 in covering relationship to the opening 12. This housing is of rectangular cross sectional Shape and includes a pair of substantially parallel side walls 15 and 16 spaced apart a distance substantially equal to the diameter of the pipe section 10 and each having one edge extending along the corresponding longitudina'l-edge of the-opening 12 in the'pipe section. The housing further includes a front wall 17 having in one end an arcuately curved recess receiving'the portion of 2,743,056" Patented Apr. 24, .1956

substantially semicircular shape receiving the portion of thepipe section lll at the corresponding end of theopening '12 and has its remaining portion arcuately curved longitudinally thereof about an axis extending transversely of the housing adjacent the midlength location of the housing and adjacent a plane parallel to ,thelongitudinal centerline of the pipe section 10 and including the edge of the front wall 17 remote from the pipe section. The .end of the rear wall 18 remote from the pipe section 10 is spaced outwardly from .the outer edge of the .front wall 17 relative to the pipe, section 1.0 and the side walls '15 and '16 are provided with sector shaped portions 20 and 21 which extend outwardly of the pipe section '10 substantially from the plane parallel .to the longitudinal center line of the pipe section and including the outer edgeof the .front wall 17 to the inner surface of the longitudinally curved portionof the rear wall 18.

The sector shaped portions 20 and 21 of the side walls and the curved rear wall 18 together provide .a structure which constitutes a .portion of the housing and has an open .end 22 of rectangular shape disposed substantially in a plane which is perpendicular to the longitudinal center line of the pipe section 10 and disposed substantially midway of the length of the housing 14.

.The rear wall 18 is somewhat wider than the distance between the side walls 15 and 16 providing flanges 23 and '24 extending outwardly of the corresponding side walls of the housing one along each longitudinal edge of 'the rear wall 18 and this rear wall is also provided at its end remote from the pipe section it with a flange 25 directed from the outer edge of the open end 22 of the corresponding structural .portion of the housing toward the pipe section 10.

The top wall 19 is a flat plate extending over .the space between "the portions of the side walls 15 and 16 betweentthe open end 22 of the rear wall structure and the front wall 17 and is provided with marginal flanges overlapping and secured to the adjacent edge portions of the side and front walls of the housing. This front wall 19'is substantially in a planeparallel to the longitudinal center'line of the pipe section 10 and to the axis of curvature of therear wall 18 and the portion of the housing covered by the top wall '19 provides a space for the reception of one end portion of a damper plate presently to be described.

The rear edge .of the .top wall 19 extends across the lower'edge of the open end '22 of the back wall structure of the .housing and a shaft 27 extends transversely through the housing 14 adjacent the rear edge of the top wall 19 'of the housing and is journaled near its opposite ends in bearing apertures provided in the housing side walls 1 5 and 16.

A damper plate, generally indicated at 28, extends transversely of the housing between the side walls 15 and extending around approximately one-half of the shaft 27 and having flanges along its longitudinal edges projecting outwardly from the shaft. The plates 30 and 31 have their end portions adjacent the shaft disposed between the opposed flanges of the clamp members 32 and 33 :and secured to these flanges by suitable means, such as' the rivets 34 extending through registering aperturesin the clamp memberfianges and the corresponding plates to rigidly secure the plates to the shaft.

The plate 30 has a length such that it extends from the "shaft 27 to the inner surfaceof the curved rear wall 18 of the housing near the end :flange 250i the 'rear' wall and the plateiil has a transversely\curvedend re- V 3- mote from the shaft 27 and a length such that it extends from the shaft substantially to the side of the pipe section remote from the housing 14 when this plate is disposed substantially perpendicular to the longitudinal center line of the pipe section. 2

The end plate remote from the shaft 27 is straight to extend transversely of the inner side of the housing back wall 18 and is reinforced by a bar extending along this end of the plate and riveted thereto.

The axis of curvature of the rear wall 18 of the housing is displaced from the axis of the shaft 27 in a direction such that as the end of the plate 30 remote from the shaft 27 moves from the end flange'25 of the rear wall toward the end of the rear wall adjacent the pipe section 10 a gradually increasing space is provided between the outer end of the plate 30 and the inner surface of the rear wall 18 of the housing to admit a gradually increasing quantity of draft checking air through the open end 22 of the housing structure and past the outer end of the check damper plate 30 into the pipe section 10 as the damper plate moves away from the open end of the housing structure.

37. The bar 39 extends through a transverse aperture in the shaft 27 near the corresponding end of the shaft and is secured in position relative to the shaft so that it extends substantially equal distances to opposite sides of the shaft and so that the bar 38 is disposed outwardly of the adjacent end of the shaft with its center line substantially intersecting the extended longitudinal center line of the shaft 27.

An angle bracket 42 is secured to the adjacent side wall of the housing at one end and has in its other end an aperture receiving a reduced end portion 43 of the shaft 27 to provide an outboard bearing for the corresponding end of the shaft and a complementary angle bracket 44 is secured to the opposite side wall of the housing and provided with an aperture receiving the adjacent end of the shaft to also provide a shaft bearing.

A weight 45 is slidably mounted on the bar 38 of the weight carrier 37 and a set screw 46 is threaded through a tapped hole in this weight and engages the bar 38 to releasably secure the weight in selected positions of angular adjustment longitudinally of the bar.

When the draft regulator is operatively connected to a furnace the pipe section 10 is substantially horizontally disposed with the housing 14 on its upper side and the end of this pipe section 10 nearest the rear wall 18 of the housing is disposed nearest the furnace and the corrugated end 11 of the pipe section 10 furthest from the furnace so that the flue gases will flow through the pipe section 10 in a direction from the uncorrugated end of this pipe section adjacent the rear wall 18 of the housing to the corrugated end of the pipe section and outside air will flow through the open end 22 of the housing structure and by virtue of its impingement against the upper sides of the damper plates 30 and 31 will be directed into admixture with the flue gases adjacent the corrugated end 11 of the pipe section 10. The pressure of the flue gases in the pipe section 10 will act against the under sides of the plates 30 and 31 and the outside atmospheric pressure acting through the open end 22 of the housing structure and through the space between the shaft 27 and the adjacent end of the top wall 19 of the housing will act on the opposite or upper sides of the damper plates 30 and 31, the pressure of the fine gases and the pressure of the atmosphere being substantially balanced at opposite sides of the shaft 27. If the rate of flow of flue gases through the pipe section 10 increases, however,

beyond a predetermined rate, the velocity of the flue gases will cause an unbalancing pressure to be exerted against the underside of theplate 31 causing the damper structure 28 to turn about the axis of shaft 27 to reduce the restriction caused by the plate 31 in the pipe section 10 and at the same time moving the outer end of plate 30 away from the inner surface of the rear Wall 18 to admit an additional regulated quanity of draft checking air between the outer end. of the plate 30 and the rear wall 18 and admix with the flow of flue gases adjacent thC rear wall 18 which air increases the pressure of the flue gases within the pipe section and reduces the rate of flow of the flue gases through the pipe section to hold the rate of the draft at a predetermined maximum value with the furnace drafts open. If the rate of flow of the flue gases be reduced, as by closing the furnace drafts, the pressure on the underside of the plate 31 will be reduced and the damper plate assembly will tend to swing about the axis of shaft 27 in a direction to cut off the flow of draft reducing air into the pipe section 10 and also move the plate 31 in a direction to restrict the flue gas passage through the pipe section to maintain the rate of draft at a predetennined minimum value.

When the damper plate assembly is moved to its maximum draft rate position, as shown in broken lines in Figure 3, the portion of the housing 14 immediately within the top wall 19 of the housing receives the plate 31 of the damper assembly so that the entire damper plate assembly is then disposed outside of the cross sectional area of the pipe section 10, enabling the flue gases to flow freely through the pipe section 10 below the damper plates 30 and 31 and the outside air to flow inwardly through the open end 22 of the housing structure, with a part of the air flow moving along the upper side of the damper plates 30 and 31 and thence downwardly and admixing with the flue gases adjacent the corrugated end 11 of the pipe section 10 and the other part of the air flow moving between the outer end of the plate 30 and the rear wall 18 and admixing with the flue gases adjacent the end of the pipe section opposite the corrugated end 11.

It is to be noted that the setting of the weight which is adjustably connected to the shaft 27 controls the initia tion of the rotational movement of the shaft in the direction to shift the end edge of the part or plate 30 of the damper out of contact with the rear wall 18 in response to a pressure of the flue gases in the conduit 10 in excess of a predetermined pressure, and also, causes the rotational movement of the shaft in the opposite direction upon restoration of the pressure of the flue gases to the predetermined pressure.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing descrip tion, and all changes which come within the range of equivalency and meaning of the claims are, therefore, intended to be embraced therein.

What is claimed is:

l. A draftregulator comprising a hollow conduit section for the flow of flue gases therethrough, an upstanding housing having a front wall, a top wall supported on said front wall, and an open lower end, positioned upon said section intermediate its ends and having the lower end in communication with the interior of said conduit section, said housing having a rear wall rising above and spaced from said top wall, the space between said rear wall and top wall forming an open inlet end for air, a horizontally disposed rotatable shaft extending transversely of saidhousing intermediate the front and rear walls and below said top wall, and a damper disposed within said housing and connected intermediate its 'ends to said shaft for rotation therewith, the part of said damper on one side of said shaft being adjacent said open end with the adjacent end edge in contact with said rear wall and the part of said damper on the other side of said shaft being wholly within said housing and below said top wall and spaced from the lower open end thereof with the adjacent end edge spaced from the front wall of said housing, said damper being movable upon rotation of said shaft in the direction to shift the end edge of said first named damper part out of contact with the rear wall in response to a pressure of said flue gases in excess of a predetermined pressure to cause movement of the end edge of said first named damper part out of contact with said rear wall and permit flow of air to said conduit section below said damper and simultaneous movement of the said second named damper part toward said top wall and restrict the flow of air to said conduit section below said damper.

2. A draft regulator comprising a hollow conduit section for the flow of flue gases therethrough, an upstanding housing having a front wall, a top wall supported on said front wall, and an open lower end, positioned upon said section intermediate its ends and having the lower end in communication with the interior of said conduit section, said housing having a rear wall rising above and spaced from said top wall, the space between said rear wall and top wall forming an open inlet end for air, a horizontally disposed rotatable shaft extending transversely of said housing intermediate the front and rear walls and below said top wall, a damper disposed Within said housing and connected intermediate its ends to said shaft for rotation therewith, the part of said damper on one side of said shaft being adjacent said open end with the adjacent end edge in contact with said rear wall and the part of said damper on the other side of said shaft being wholly within said housing and below said top wall and spaced from the open lower end thereof with the adjacent end edge spaced from the front wall of said .housing, said damper being movable upon rotation of said shaft in a direction to shift the end edge of said first named damper part out of contact with said rear wall in response to a pressure of said flue gases in excess of a predetermined pressure to cause movement of the end edge of said first named damper part out of contact with said rear wall and permit flow of air to said conduit section below said damper and simultaneous movement of said second named damper part toward said top wall and restrict the flow of air to said conduit section below said damper, and a Weight adjustably connected to said shaft for controlling the initiation of the rotational movement of said shaft in said direction and for causing the rotational movement of said shaft in the opposite direction upon restoration of the pressure of the flue gases to the predetermined pressure.

References Cited in the file of this patent UNITED STATES PATENTS 1,307,950 Anderberg June 24, 1919 1,943,342 Mortimer Jan. 16, 1934 2,193,274 Ekman Mar. 12, 1940 

